// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/task_scheduler/test_task_factory.h"

#include "base/bind.h"
#include "base/bind_helpers.h"
#include "base/callback.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/sequenced_task_runner_handle.h"
#include "base/threading/thread_task_runner_handle.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace base {
namespace internal {
    namespace test {

        TestTaskFactory::TestTaskFactory(scoped_refptr<TaskRunner> task_runner,
            ExecutionMode execution_mode)
            : cv_(&lock_)
            , task_runner_(std::move(task_runner))
            , execution_mode_(execution_mode)
        {
            // Detach |thread_checker_| from the current thread. It will be attached to
            // the first thread that calls ThreadCheckerImpl::CalledOnValidThread().
            thread_checker_.DetachFromThread();
        }

        TestTaskFactory::~TestTaskFactory()
        {
            WaitForAllTasksToRun();
        }

        bool TestTaskFactory::PostTask(PostNestedTask post_nested_task,
            const Closure& after_task_closure)
        {
            AutoLock auto_lock(lock_);
            return task_runner_->PostTask(
                FROM_HERE,
                Bind(&TestTaskFactory::RunTaskCallback, Unretained(this),
                    num_posted_tasks_++, post_nested_task, after_task_closure));
        }

        void TestTaskFactory::WaitForAllTasksToRun() const
        {
            AutoLock auto_lock(lock_);
            while (ran_tasks_.size() < num_posted_tasks_)
                cv_.Wait();
        }

        void TestTaskFactory::RunTaskCallback(size_t task_index,
            PostNestedTask post_nested_task,
            const Closure& after_task_closure)
        {
            if (post_nested_task == PostNestedTask::YES)
                PostTask(PostNestedTask::NO, Closure());

            EXPECT_TRUE(task_runner_->RunsTasksOnCurrentThread());

            // Verify TaskRunnerHandles are set as expected in the task's scope.
            switch (execution_mode_) {
            case ExecutionMode::PARALLEL:
                EXPECT_FALSE(ThreadTaskRunnerHandle::IsSet());
                EXPECT_FALSE(SequencedTaskRunnerHandle::IsSet());
                break;
            case ExecutionMode::SEQUENCED:
                EXPECT_FALSE(ThreadTaskRunnerHandle::IsSet());
                EXPECT_TRUE(SequencedTaskRunnerHandle::IsSet());
                EXPECT_EQ(task_runner_, SequencedTaskRunnerHandle::Get());
                break;
            case ExecutionMode::SINGLE_THREADED:
                // SequencedTaskRunnerHandle inherits from ThreadTaskRunnerHandle so
                // both are expected to be "set" in the SINGLE_THREADED case.
                EXPECT_TRUE(ThreadTaskRunnerHandle::IsSet());
                EXPECT_TRUE(SequencedTaskRunnerHandle::IsSet());
                EXPECT_EQ(task_runner_, ThreadTaskRunnerHandle::Get());
                EXPECT_EQ(task_runner_, SequencedTaskRunnerHandle::Get());
                break;
            }

            {
                AutoLock auto_lock(lock_);

                DCHECK_LE(task_index, num_posted_tasks_);

                if ((execution_mode_ == ExecutionMode::SINGLE_THREADED || execution_mode_ == ExecutionMode::SEQUENCED) && task_index != ran_tasks_.size()) {
                    ADD_FAILURE() << "A task didn't run in the expected order.";
                }

                if (execution_mode_ == ExecutionMode::SINGLE_THREADED)
                    EXPECT_TRUE(thread_checker_.CalledOnValidThread());

                if (ran_tasks_.find(task_index) != ran_tasks_.end())
                    ADD_FAILURE() << "A task ran more than once.";
                ran_tasks_.insert(task_index);

                cv_.Signal();
            }

            if (!after_task_closure.is_null())
                after_task_closure.Run();
        }

    } // namespace test
} // namespace internal
} // namespace base
